Question

A ball was traveling at a speed of 15m/s.
If it has been hit by a bat with a speed of 20m/s in opposite direction then it's energy changes by 8.75 J.
Then calculate the change in momentum.​

Answer 1

Solution:-

A per the given data ,

• Initial speed of the ball (u) = 15 m/s

• Final speed of the ball (v) = - 20 m/s (  the ball is moving in opposite direction )

• Change in kinetic energy = 8.75 J

Change in kinetic energy is given by ,

⟹ Δ KE = mv²/2 - mu² /2

⟹ Δ KE = m/2 ( v² -u²)

⟹ 8.75  = m/2 ( 400-225)

⟹ 8.75 = m x 175 /2

⟹ 8.75 = m x 87.5

⟹ m = 8.75 / 87.5

⟹ m = 0.1 kg

The mass of the ball is 0.1 kg

Now let's find the change in momentum of the ball ,

⟹ ΔP = mv - mu

⟹ ΔP = m (v - u )

⟹ ΔP = 0.1 ( 20 - 15)

⟹ ΔP = 0.1 x 5

⟹ ΔP = 0.5 kg m /s

∴The change in momentum of the ball is 0.5 kg m/s